The answer would, I suppose, depend on how you define "inexperienced", "required", and "training".

You can go to your local climbing gym and pay somebody to put on your harness, tie you into a top rope, and belay you while you flail your way up the wall. Are you climbing without training? Are you even climbing at all?

To climb *safely* requires some level of technical skill. It can be taught by a guide, picked up from more-experienced climbing partners, even learned from a book. What constitutes "training"?

How would such training be required? By law? How is competance judged?

As Dave's response indicates, this question really has to be put into context. This turns out to be a question that has been debated and argued for decades, and is a real can of worms. You might refer to my post below about use of "automatic belay devices" and a developing view of their use by the manufacturers. Here are some of the parameters you need to define:

Dave's list - what do you mean by "inexperienced", "training", "climbing", "required"?

There are all sorts of health and safety and liability issues here. I am a Climbing Director for Boy Scouts of America, and thus am in charge of training adult leaders to become climbing instructors. That points out a couple other issues -

Who will be doing the training (what qualifications are required for the trainers, and how will they be "certified"?)?

How much training will be required of the "inexperienced climbers", and how will it be determined that they have met the "requirement" of sufficient training?

What is the venue for the climbing - rock in a natural setting, glacier, ice (frozen waterfall), a commercial gym with an artificial wall, a home gym, a climbing wall or tower constructed by a private individual?

Another aspect of the venue - government land (National Park or Forest, state park or forest, city or county), commercial enterprise, private property, ....? Who has the responsibility and liability for maintenance, rescues, first aid, ambulance, etc?

Depending on the answer to the rock/ice/artificial question, what skills (and demonstrated minimum level of competence) would be required?

On the "required" question, when requirements of any kind are imposed, someone assumes responsibility and liability. You will find that in most venues, if a person is to go climbing on their own (or in their own group), there are no requirements for training or experience, but instead a list of recommendations. For example, to climb Denali, the only requirements are to register ahead of time (time limit depends on whether you have been on the mountain before or not) and sit through a briefing by one of the climbing rangers. The ranger will ask about your experience and the gear you have with you. If he/she judges that you are lacking in some areas, you will be offered advice on needed preparation and gear. However, you will not be forbidden from climbing the mountain. On the other hand, if you get in trouble and have to be rescued, you may have a severe financial penalty.

Another example - if you show up in Yosemite Valley, you can just walk up to one of the cliffs and start climbing. There are notices posted and briefings available from the rangers and other climbers. But no one is going to stand next to the walls and check your credentials. You take responsibility for yourself. There are some activities which have proven to involve such high risk that the rangers will take measures to stop you (BASE jumping from the cliffs, for example, which has claimed several lives), but generally you are on your own.

In some areas, there is not even rescue service available, much less any requirement for training or experience.

As Dave indicates, if it is a commercial gym or portable climbing tower, all that is needed is for the gym personnel to attach you to the belay setup and provide a belay. In an increasing number of these, the belay setup is entirely automatic, so all that is needed is for the climber to put on the harness, have it inspected by the operator, who clips you in, and away you go. In such case, this is how you get your training and experience - nothing previous is needed.

Most in the climbing community oppose restrictions and requirements for training and gear. The vast majority feel that the individual should be responsible for him/herself, which includes any training, furnishing gear, and, something the general public does not seem to understand (and the media grossly misunderstand), self-rescue in case of problems. Yes, sometimes something happens that outside assistance helps, and sometimes going to a new area, there are risks that are not immediately apparent to the first-time visitor. But the general feeling is that you search out the information (called "beta") on the area and any local risks as part of your personal responsibility. And the climbing community usually pulls together to organize mutual aid (most members of S&R units are climbers themselves)

By the way, the statistics on S&R are that the vast majority of incidents are hikers, casual tourists, and lost kids, with a very tiny percentage being climbers (the media usually play up any rescue as involving a "climber", even if it is a tourist who left his car in sandals, shorts, and a cotton T-shirt, despite the forecast incoming snow storm).

That is a lengthy way of answering. The short answer you will get from the climbing community as a whole is a resounding "NO!". As Dave noted, the interested novice can get training from commercial guide services, climbing clubs, and experienced friends. Most people have the sense to seek out training themselves, no need for "required training".

The answer you will get from the media and general public is yes, save these demented crazies from themselves.

I spent many years as a scuba instructor. Public policy and insurance liability has led to the requirement that divers be trained and certified by a recognized organization before they can purchase air at a shop or go diving with a tour, such as on a boat, in most countries. The need for a compressor to fill your tank creates a "check point" which separates the trained from the untrained. If you had your own compressor (which some people do), then nothing would stop you or your friends from diving without ever being certified.

Climbing has no such "check point." Anyone can buy climbing gear and head off into the wild. There is no one to stop them, except their own self-awareness of their limitations.

However,I've been diving with certified divers who were so afraid of a little wind chop that they wouldn't get in the water. A basic course doesn't mean that the person has common sense or the natural affinity for the sport that will keep them safe.

Trying to monitor or license climbers is virtually impossible. I suppose a license could be required to climb in a national or state park, but then again, from my experience, a basic class doesn't mean you're ready to tackle anything. I have taken a basic mountaineering course and know the basics, but if go climbing again, the only person that will matter to is me and whoever I'm with. Having some kind of a certificate is less important that the knowledge and experience I have.